TO HELP THE AIRMAN IN A FOG

New Zealand Herald, Volume LXXIV, Issue 22819, 28 August 1937, Page 9 (Supplement)

TO HELP THE AIRMAN IN A FOG

A NEW help to the airman in finding his height above the ground is promised. At present his height recorders are on the principle of the barometer and show only how high the machine is above sea-level. But this is of small use to him in fog or in mountainous country. The new device, invented by Lieutenant L. P. Delsasso, of the United States National .Research Department, adopts the same idea as the sound recorders of ships at sea, which send sound waves to the sea-bed and measure its distance by the time taken by the sound waves to rebound. At present the device to measure how long the sound waves take to return to the pilot's cockpit is hampered by the terrific sounds arising from -the plane's engines, and will not register

differences much above 700 feet. But this may be improved upon by using special sounds of high intensity for the echo. Furthermore, the apparatus, weighing 401b., is too heavy; but that also may be remedied. No earphones are required. A simple moving point on a dial in front of the airman tells him his height at lower levels, and registers accurately to 50 or 100 feet in fog. It may also signal the nearness of a neighbouring hill.